[PATCH V2 0/1] Enable/Disable NVMe quirks via module parameter

[Maurizio Lombardi]

Recently, some of our customers were very vocal about wanting an
easy way to enable or disable specific nvme quirks.

I recall that during the ALPSS conference this topic has been briefly
discussed, and it was proposed to use the generic PCI sysfs "new_id" entry
to manipulate the quirks.

However, in some cases a quirk may prevent the system from properly booting,
the kernel may hang or fail to mount the root
filesystem before the system reaches a state where new_id can be written,
this makes this solution not exactly user-friendly for end users.

In particular, boot-time hangs have been reported involving the
bogus_nid quirk.

Therefore, I have been asked to re-propose this module parameter approach
with a few modifications suggested by Daniel Wagner.


# dmesg | grep nvme
[    0.000000] Command line: root=/dev/vda1 console=ttyS0,115200n8 nvme.quirks=1b36:0010:^bogus_nxid
[    6.732692] nvme: unrecognized quirk bogus_nxid

# cat /sys/devices/pci0000:00/0000:00:05.0/nvme/nvme1/quirks
bogus_nid
                                                                                                                                                                                                                         
# dmesg | grep nvme
[    0.000000] Command line: root=/dev/vda1 console=ttyS0,115200n8 nvme.quirks=1b36:0010:^bogus_nid,no_apst
                                                                                                                                                                                                                         
# cat /sys/devices/pci0000:00/0000:00:05.0/nvme/nvme0/quirks                                                                                                                                             
no_apst

Maurizio Lombardi (1):
  nvme: add support for dynamic quirk configuration via module parameter

 .../admin-guide/kernel-parameters.txt         |  13 ++
 drivers/nvme/host/pci.c                       | 164 ++++++++++++++++++
 2 files changed, 177 insertions(+)

-- 
2.52.0